Extension ladder



Oct. 23, 1951 M. SMITH 2,572,775

EXTENSION LADDER Filed March 24, 1949 l 2 SHEETS- SHEET 1 Oct. 23, 1951M. SMITH EXTENSION LADDER Filed March 24, 1949 2 SHEETS--SHEET 2 1N VENTOR. /Vtfrzw 5mm BY w, 6M, ym

Patented Oct. 23, 1951 .mesne assignments, to McCabe-Powers Auto Birdy'09 S;tfl0iiis, 1Mo... a entnommen .0f

Missouri Application March 24, 1949, Serial No.-83,1-91

This invention relates to an extension ladder provided withmeans forreadily effecting the extension of one section with reference to theother. The object of the invention is to provide not only simple meansfor-effecting fthe-extension but also means lfor readily controlling thevdescent of'the extendable portion bygravity, so that there will `be nodanger of injuring the operator or damaging the apparatus. My extensionladder is .well adapted for mounting in any suitablefmanner as forexample-on a vehicle where it may lie in 'a horizontal position fortransportation and be raised into an inclined or approximately verticalposition for use.

The invention is illustrated in the drawing hereof and hereinafter fullyexplained and the essential novel features are summarized in the claims.

In the drawings, Fig. 1 is a side elevation of my extension ladderindicated as mounted on a vehicle, part of which is shown; Fig. 2 is afragmentary elevation on a larger scale of the ladder in a planetransverse to Fig. l; Fig. 3 is a side elevation of mechanism forcontrolling the extension; Fig. 4 is a cross section through theelevating mechanism, in a plane indicated by the line 4-4 on Fig. 3;Fig. 5 is a fragmentary sectional elevation on a larger scale of aportion of the operating mechanism shown in Fig. 4.

The base portion of my extension ladder indicated at Ill in Figs. 1 and2 comprises a pair of parallel side bars and various cross bars I I. Theextension member I2 also has a pair of parallel side bars connected bycross bars I3. The side bars of the extension are slidably connected, asby tongue and groove or other suitable means, with the side members ofthe base I0.

I have indicated the base I as mounted on suitable supporting mechanismcarried by a standard rising from a vehicle 2|. The supporting mechanismindicated in general at 22 is not shown in detail as it constitutes noportion of the present invention. It may be constructed in accordancewith Patent No. 2,422,507, issued June 17, 1947 to my assignee, TheAmerican Coach & Body Company, as assignee of Herman J. Troche and EltonJ. Farrar.

To effect the extension of the ladder member I2 along and beyond themember I0, I provide a cable anchored at its upper end to the upperportion of the base ladder I0 as, for instance, by looping around a topcross rod I I of the base ladder. This cable then extends along theextension ladder to the lower portion thereof where it passes around twopulleys 3| carried by brack- 2 Claims. (Cl. 25p-14g) ets f32 extendinginwardlyfrom .the side barsfof the extension ladder. rThe cable thenpassesupwardly to a pulley 33 and .also secured ttowthe uppermost crossbar .II and'thence downwardly to a winding drum .40 carried'bythebasemember I0.

The windingdrum :40, .shown in `detailin Fig. 4, comprises ahollowbarrel 4I and two disc heads 42yandx43. These :heads aretightly mountedon a rota-ry shaft .45 journaled in bearings -46 4and 41 carried bybrackets 156 and 51 respectively. The Ibrackets .in turn Iare Acarriedby the side members of the base ladder I0. I have shown a collar 48welded to the head 42 and keyed to the shaft 45 so that the drum islocked to the shaft to rotate therewith while allowing the shaft to beshifted slightly longitudinally thereof, as indicated by the brokenlines in Fig. 4 for a purpose hereinafter described. A suitable disccrank 5U slidably keyed to the shaft, furnishes means for rotating theshaft and drum to wind in the cable 30 and thus cause the extension ofthe ladder I2.

Between the hub of the disc crank 50 and the bearing 41 I mount adistance sleeve 5 I. Threaded on the shaft on the outer side of the hubof the disc crank is a hand wheel 53 which bears against the hub. Acotter pin or other suitable stop 55 prevents inadvertent removal of thehand wheel 53 from the shaft. Secured to the inner face of the bracket5'I is a rub disc 58 with which the drum head 43 may be caused tocontact by a slight lateral shifting of the drum.

Fig. 4 shows in full lines the drum and shaft in position with the drumhead 43 in snug engagement with the friction disc 58, which is thebraking or lowering position. This view indicates in broken lines theposition of the drum and shaft during the raising operation.

In the operation of my invention, the rotating of the hand crank rotatesthe shaft 45, the hand wheel 53, the shaft 45 and the drum as a unit towind in the cable to raise the extension. When the extension isdescending by gravity the same is controlled by the hand wheel 53,which, being turned manually on the screw thread of the shaft, operatesto pull the shaft outwardly and thereby shift the drum slidably towardthe hand wheel causing retarding friction between the head 43 and therub disc 58 on the bracket 51.

The friction, produced by the braking disc may, if desired, besuiiicient to firmly hold the extension member elevated or it may besuch that the extension gradually and slowly slides down within the baseladder.

A suitable gravity latch (not shown) may if desired be applied to theextension ladder to overhang successive rungs of the base ladder andhold it positively in any elevated position which may be given to it,until the latch is manually thrown to idle position preceding thedescent.

It will be seen that my elevating mechanism is very simple inconstruction, readily operated to effect the extension desired withoutrequiring much force by the operator on the handle 59 of the disc crank.During such elevation the shaft and drum rotate freely without bindingfriction. On the descent of the ladder the mere turning of the handwheel 53 controls descent so that the ladder may gradually return to itsinitial position without danger to the operator or causing damage to themechanism.

I claim:

1. The combination of a base, a member to be raised, a pair of bearingscarried by the base, a shaft rotatably mounted in said bearings, a drumbetween the bearings secured to the shaft, a cable connecting the drumand said member, a hand crank keyed to the shaft in a manner to allowsome movement between them axially of the shaft, a member threaded onthe shaft and bearing against the hub of the hand crank, means to resistaxial movement of the hand crank toward the adjacent bearing, and afriction device between such adjacent bearing and the adjacent end ofthe drum adapted to coact with the drum when the shaft is shiftedaxially.

2. The combination of a base, a member to be raised, said base having apair of bearings, a shaft rotatably mounted in said bearings, a drumbetween the bearings tightly keyed to the shaft, a cable wound on thedrum and leading to said member over a pulley carried by the base, acrank keyed to the shaft in a manner to allow axial movement of theshaft through the crank, a distance sleeve between the hub of the crankand the adjacent bearing, a hand Wheel threaded on the shaft and bearingagainst the outer side of the hub of the crank, and a friction discbetween such adjacent bearing and the adjacent end of the drum, adaptedto frictionally clamp the drum to the bearing when the shaft is shiftedby the hand wheel.

MERTON SMITH.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Smith Nov. 21, 1950

